How do radical cations react? This answer to this question defines the boundary conditions for the intermediacy of radical cations in a variety of oxidative reaction pathways. For instance, radical cations are implicated as intermediates in the oxidative biochemistry of polynuclear aromatic hydrocarbons to form powerful carcinogens. Despite some "obvious" energetic and stereochemical imperatives, only recently has a quantitative description of reactivity in radical cations begun to emerge. The goal of this research is to explore in a systematic way how the structure and environment of a particular hydrocarbon radical cation determine the way in which it ultimately decomposes to isolable products, either via proton loss or nucleophilic attack by water or other nucleophiles. Known carcinogens or hydrocarbons structurally related to these will be synthesized, and the products resulting from oxidation of these hydrocarbons will be isolated. Rates of decomposition of the intermediate radical cations will be measured via cyclic voltammetry. Competition studies will determine the importance of a stereoelectronic effect on proton loss. Other variables to be investigated include oxidation potential, position of substitution, isotope effects, and nature of the oxidant, whether enzymatic or nonenzymatic. This information will be used in a direct way to determine how the microenvironment of a radical cation may lead to a particular decomposition pathway with either deleterious or innocuous effects on the human organism.